Emqby leon chaj



Y Nowp, 1928.

l1,690,719 E. L. CHAFFEE ET AL METHOD AND MEANS FOR SECRET RAD-IOSIGNALING Original Filed March 3l. `1922 4 Sheets-Sheet 1 Nov. 6, 1923. y 'y 1,690,719

E'. L. CHAFFEE ET AL METHOD AND MEANS FOR SECRT RADIOSIGNALING I original Filed March' 51. 1922 4 sheets-sheet 2 f I wuamfcozs Emor'y Leon Chaffee' i E/ 's 5: P v t gn #nur GMM/mai; on Hrm? on Nov. 6, 192s. b 3,690,719

E. L. CHAFFEE ET AL l METHOD AND MEANS FOR SECRET RADIOSIGNALING original Filed Maron 31; 1922 4 sheets-sheet 5 Snow/bow Nov. 6,*l I 1,690,719

E. L. CHAFFEE ET AL METHOD AND MEANS FOR SECRETv RADIOSIGNALING I Original Filed March 51. 1922 "4 5116915-31991, 4 i

Hq- Q- Patented Nov. 6, 1928.

narran srarasf8f PATENT f oF EMoEY LEON CHAEEEE, or EELMON sacnusa'rms, AssIeNoRs 'ro .ton cHUsETTs. v

METHOD am) MEANS ron Application led March 31, 1922, Siehe-1 Some of the objects of the present linvention are to provide an improved met fod of transmitting radiant signaling energy f to provide improvements in means for transmitting radiant signaling energy; to provide an improved method of receiving rad1- ant signaling energy; to provide improvements innieans for receivingradiant signaling energy; to provide an `improved system of communication by `radiant energy whereby increased secrecy is afforded; and to provide other objects which will appear in the following description taken vin connection with the accompanying drawings.

Referring to the drawingsz 5 Figure 1 shows diagrammatically one form of transmitting station embodying the features of our invention; Fig. 2 shows diagrammatically one form of receiving station for receiving radiant energy according to the invention;

Fig. 3 is a chart showing typical varriations in frequencies of currents produced by the system of Fig. 1; g Fig. 4 isv a chart vshowing anartifioial wobble produced by a portion of the wobbi er of Fig. l; i y

Fig. 5 is a chart showing a second wob'le produced by a different portion of the wobbler of Fig. l;

Fig. 6 is a chart showingA the total wobble patterns produced by the currents charted in the two parts of Fig. 3 in combi-nation 4with Figs. 4 and' respectively;

Fig. 7 is a chart showing' the true mes-v sage in duplicate; Fig. 8 corresponds to Fig;v 6 except that the differences between the two portions of the chart are proportional -to the message current charted in Fig.' 7;:f

Fig. 9is a chart of the beat note pattern produced at the receiving station by the total wobble pattern due to the artificial and message wobble (Figs. 6 and?) lin combination with heterodynes producing currents of fre uencies substantially midway of the wobble range;

Fig. 10 gives the differences betweenthe two portions of Fig. 8; arid y Fig. 11 isthe envelope of Figi 10.

Referring Vto the drawings, andanore particularly 4to Fig. l, there isgshow'n a trans-v mitting station comprisin an '/antenna 10 connected to earththroug a v winding of a coupling 11. .The coupling 1.1

I secondary -29 and 30. One

yating in close proximity to a 1,690,719 Flor..

smmmonn, In., or GLOUCESTER, mesa# SECRET RAIDIOSIGN'ALING. l No. $48,513. Renewed March 16, 192@I primary windings 12 `and 13. 12 is included in the plate circuit of a threeelectrode 'vacuum tubev or thermionic Vvalve 14. Similarly; the Lwinding 1,3 isiincluded 1n the plate vcircuit of a second three-electrode vacuum tube or thermionic valve 15. Each of the devices 14, 15 comprises an evacuaft'edk bulb having a heated. filament, 16

ha a, palr of Tle winding ANnELLIsoN s. PURINGTON, oF EosfroN, isfmsforming aI hot cathode to causeemission of l electrons, a plate anode -17 uponfwhiehthe electrons impinge and a grid are The grids 18 of the devices 14 and condenser to the circuit of a usual three-elecgrode ther` mionic device 24. The grid of th is connected through a suitable 25, shunted by a .so-called winding 27V device 24 .condenser pling 28.

The plate of the device 24 is connected to I the primary winding 29. of th the primary winding` 30 of t e coupling 23, and a plate potential batteryI or D. C. generator 31 in series. In shunt with the winde coupling 28,

ings 29 and 30 collectively is an adjustable condenser 32 of conventional construction,

and also a wobbler mechanism. 33. The

wobbler mechanism comprisevsmechanically l driven means for periodically varyingadditional capacities in shunt with the windings of these capacities 34 is intermittently nected into circuit periodica arm 37. Another variable sists of a rotatable, doublelse'gment 38 operrelatively fixed,

ly'by a contact-v arcuate segment 39. 4

P late power for theelectnon' devices 1 4 and A s suppliedby an additional 'three-electro e the giid circuitfof the is a usual capacity con- A 18 for controlling the passage of the electrons/ id leak 26, to a o y 'a `second couconnected into circuitby a con-I,

acity 36 is conloo thermiomc deviceAO.- Inc1i1ded;in

last named device Y401 gndecondenser 41 and grid leak' 42, and awinding 43 of a coupling The plate circuit of the device 40 `includes a" second winding 45 of the coupling 44 and a usual plate potential battery 46. `The ZES )late potential may be supplied, if desired, a suitable C. generator in place of the battery 46.

A pair of windings 50, :7l of the coupling 44 inductivcly coupled to the windings 43, 45 thereof are connected respectively to the windings l2 andl ofthe coupling ll, The windings 455 and 45 Yare coupled closely to the windings 5() and 5i but loosely to each other. A common conductor .'33 joins one terminal ot' each of the windings 50, 5l to the stabilizing or return Wire 54 ot the system. j

The potential stabilizing conductor 54 intcrconnects the various negative terminals of the several therinionic .devices of the transmitting system, and may be connected to a ground (not shown) for maintaining zero potential above'ground thereon.

For determining the frequency of the oscillation generator 40, there is provided an adjustable condenser 60 in shunt with the windings 50, 5l collectively. The electrical characteristics of the closed, oscillatory circuit which includes the windings 50,51 and the condenser 60 may be adjusted to cause the generator 40 to produce oscillations of a desired fre uency m. In shunt' with each of the Win ings 50, 51 there may be prothe drawings.

vided, if desired, a by-pass condenser such as 611, of relatively low electrostatic capacity; under certain conditions, however, the capacity between the adjacent turns. of the windings 50, 51 is sufficient, and this capacity is represented by the condensers being dotted to assist in a ready understandingr of For varying the frequency of the oscil- 'lations produced by the device 40, there is included acondenser' 63 and a control key or switch 64. When the key 64'is closed, the i condenser 63 is connected iii shunt with the` The receiving system shown infEg. .2 in-Qv cluds a pair of receivingr loops 70, 'Il adapted to receive radiant energy from thedirection in which thc antenna 1() of the transmitting svstem lies relative to the receiving station. '.lhe electrical resonance ofthcscloops may be adjusted by a corresponding .pair ot vari-` able condcnsers 72, 73 connected in shunt with the loops, respectively, and Storming therewith a paixof closed oscillatory ircuits 74, 75. T he condensers i2 and. 75 of tire closed, oscillatory circuits 74' rsind 7 5 are adjusted so that the receivingloops and .pressed oscillations.

Legame f '71 in the input circuit of the thcrmionic de-` `For instance, satisfactory reception can be obtained with` the receiving system shown in Fig. E2, where the'y frequencies of the oscilations approximate 1,000,0(M) cycles per -second, and wobbling of the respective frequencies is effected through a range of 5,00() cycles per second.

For detecting, rectifying or amplifying `the received energy, there is provided a three electrode, thermionicdevice 80. The grid circuit ol the device includesy the two oscillatory circuits 74 and 75 in series, and a portion oi a potentiometer 8l, whereby the grid potential may be varied as desired'.4

The arrangement is such that rectifiedV im` pulses are produced in thc output circuit of,

the device 80, which, includes a conductor 82, a clos-cil oscillatory'circuit 83, and ausual/source of' plate potential 84. The.

circuit 83' is preferably `tuned 4to the difference between the transmitted Waves when the key Gais closed,- that is, to a frequency 2in-2.1, and its tuning may be varied in a well known manner as by a variable condenser. The circuit 83 'may be coupled to thev grid circuit of a second, three electrode thermionic device 85 by meansV of any der sired method of coupling, as for example, resistance, capacitative or inductive. As shown, an inductive coupling is employed.

The output circuit ol' the device 85 may be similarly-coupled to -the input of a third, three-electrode therni'onic device 90 und the loo output circuit therci to the input of a i'o'urth lhermionic device 91.@The arrangement illustratedl is a s0-called cascade arrangement of vacuum tubes, and may be varied in its arrangement 'without departing from the spirit ol the invention. For eX- ample, the number of tubes in the series may he reduced fir-increased by a desired number, in a manner o'bvious to those skilled in the art.

The final device 91 is arranged as a socalled `autmlyne whereby regenerative, continuous oscillations are )reduced in its circuit, caus'nfr beats with the original im' Currents of thebeat frequencies may be arranged to actuatc a telephone receiver 95 as shown, or any devrsircd controlled device-may be used.

I nthe following description` algebraic symbols will be employed for indicating cer'- `tain values, and by wayof example axspecific value thereof will be given. to illustrate one Way 1n which theinvention may be practised.

With the varying capacity 38, 39 of the Wobbler 33 in operation, but the contacts 35 and 37 thereof inactive, the circuit of Fi 1 produces in the antenna represent changes in frequencyv of the 'two series ofv oscil ations respectivelyand are spaced apart by an amount dependent equal to twicetlie frequency ofthe oscillating de-` diated of frequencies which are unchanged over the period' of time recorded.V Operation of the Wobbler 38, 39, however, cyclically varies the frequency of each 'of the Waves gradually through a predetermined range, and these' cyclical variations `in frequency follow the curves shown ingFigure 3. The capacity 34, is selected -so that with all other conditions constant, the frequency of oscillation of thedevice 24 will e varied by a v alue f by connecting the capacity 34 into circuit. The contact 35 con trols this connection, and is arrangedto open and close the connection in accordance with a dash and dotpattern, such as shown in Fig.4.

rlhe capacity 36 is selected so that with all other conditions constant, the

frequency of oscillation of the device' 24 will be varied by a value g by connecting rthe capacity 36 into circuit. The capacity 36 should preferably' be 'different from 34, so that 4the frequency change g will be ditferent from f. The Contact 37 controls the connection of the capa-city .36 linto circuit, and is arran ed to open and close the connection in accordance with a dash and dot rescntation assumes that the capacity 36 is greater' 'than capacity 34. l

Numerical va uesaccording to the following table may be assigned to the algebraic symbols mentioned by way of example, but it is expressly understood that the scope of the invention is not to belimited thereby.

Any usual radio frequency may be eniployed, preferably relatively high compared with the value 7a. With the wobbler 33 and key 64 inactive, the master tube' 24 produces oscillations locally which vapproxiinate the radio frequency to' be used. AMeans ...including the couplers ll and 44 and the (g does not=f).

two series o Kos-l clllatioiis the frequencies of which varyas' shown in Fig. 3, the two curves of which if it Were 2m' 'wh en the ordinary detector or rectifier is not since the difference frequencies pattern such as shown in Fig. 5. rlhe diagrammatic rep- 'station of a form heretofore ployed.

result therefrom -two series of' oscillations impressed upon the .ether, ech series of which differs in frequency from the 'mastercircuitoscill'ationfrequency by an amount m. A the operation of the transmittin station -of Figi 1, the entire wobbler-33 eing in operatioghthere' are produced in the. antenna, co-existing currents whose frequency variations are shown in Fig. 6. The two lortions are similar in shape, the shape -eing determined by the summation of the effects of the elements 35, 37 and 38 of the Wobbler 33 upon the master 'circuit frelquency.

The true message is now transmitted by operating the key 64 in accordance therewith. This decreases the .difference frequency, because closure of the keyv 64 connects into circuit the capacity 6 which decreases the period of oscillation of 'the device by the amount a. The message variation is indicated diagrammatically in Fig. 7.

The variations in frequencies of the oscillatory energy impressed upon the ether While transmitting the message, are shown diagramniatically in Fig. 8. Here the two curves differ from one another by an amount key 64 is in its open position, but by an amount 2in-#2n when,` is in its closed position. The frequency 2m-2n is preferably above audibility.V .v

Reception by means of a circuit using an possible 2m and Zm-Q//i are super-audible.

To indicate that the true message,- cannot be read by beat/reception there visshown in artificial web ile of Fig; wobble of Fie. T

beat note obtained ley tuning the local autodyiie or lietcrodyne of an ordinary receiving set to'a frequency midway ot' the range ot' the lower part of Fig. 8. Similarly the true message cannot be read by tuning to the F ig. 9 thesequence of beat tones due tothe' 6 and the message his curve shows the other wobbled frequency shown in the upper part of Fig. 8nor by any other adjustment of the receiver.

Thus it is apparent that it is impossible to receive'thc true, message at a receiving It will be apparent from the foregoing that the receiving station of Fig. 2 is arto be responsive to changes in the d iiierence ybetween the frequencies of oscillations received by the loops '70 and 7l. The 'iferencesare shown diagrammatically in ig. 10 in which each vertical line' represents the respective difference between the curve of the upper part of Figf8 and that of the lower part.

The envelope of the difference frequencies the key .64

generally em'` y is indicated in Fig. 11. Its similarity to the true message of Fig. 7 is obvious. dyne 91 of Fig. 2 is tuned so as to produce beats of audible frequency and thus the device 95 produces the signal of Fig. 11.

' The construction illustrated and described herein is merely what we now =consider tolie the preferred embodiment of our invention and it is therefore to be distinctly understood that we do not limit ourselves thereto as manyl changes may be made in point of detail. and other embodiments than' those shown may be resorted to Without deviating from the true spirit and scope of ourinvention as defined by the appended claims.

What is claimed is: 1. The method of producing radiant energy for the transmission of intelligence which comprises generating a pair of alter c. mM

natingcurrents of unlike frequencies, wobbling said currents similarly so that the *frequency difference thereof normally remains substantially constant,'and'transmitting a message .by vvarying said difference frequency.

2. rl'he method of producing radiant energy for transmitting intelligence which` comprises generating a pair of alternating currents of unlike frequencies. wobbiing said currents similarly so that the frequency dif- .ference thereof normally remains substantially constant, and transmitting a message by manually varying said difference frequency.

3. The method of producing radiant energy for transmission of intelligence lwhich comprises generating a pair of alternating curi-mits of unlike frequencies, wobbling said currents similarly so that the frequency difference thereof normally remains substantially constant, changing said difference frequency to transmit a signal' and maintaining said changed difference frequency substanlially constant for the duration of a signal.

4. In a system for the transmission 0f iny telligence, means for generating two wobbled alternating currents having frequencies normall 1 differing from each other by a substantially constant amount, and means for modifying sa'id difference to transmit asignalA arranged to maintain said modified difference substantially constant for the duration ot' a signal.

5. The `method of transmitting intelligence which comprises transmitting two alternating currents of unlike frequencies, normally maintaining the difference between said frequencies substantially' constant while varying the said frequencies,` and changing said frequencies to change the difference for transmitting a message.

6. The method of transmitting intelligence which comprises transmitting two wobbled series ofA oscillations of unlilie frequencies normally differing from each other The auto? by a substantially Yconstant amount, changl ing saidi difference inaccordance with a mcs-v c Sage, selectively receiving said series of oscillations and pioducmg an indication by the combined action of said series of oscillations.

7. The method for producin f radiant energy for the transmission o intelligence which comprises generating two series of oscillations having frequencies differing from each other by an amount above good 'audibility, wobbling `said series of oscilla'- detecting them to produce a qtirlient o'f a, frequency equal to the ditl'ereiy etween the frequencies of said series of` ci'ilations,

and detecting and indicating saidcurrent.

8. The method of producing radiant energy for the transmission of -intelligence which comprises generating two alternating currents of unlike frequency', wobhling said currents similarly so that the frequency difference thereof normally remains substantially constant, andtransmitting a message by modifying the frequencies of saifl eurrents to change the frequency differ-ence.

9. The method of producing radiant fen-y ergyfor transmitting intelligence w lng comprises generating apair of alternating currents of unlike frequencies, wohbling sliid currents similarly so that the frequency dif-v ference thereof remains substantially constant, and transmitting a message my manually modifying the frequencies of said cur-l rents to produce a different dierence frequency.

` 10. A system for transmitting radiant energy, comprising means lfor producing local radio oscillations, means' for wobbling the frequency of said oscillations, means `for producing therefrom and impressing on the ether a `plurality of series ot waves having frequencies-.differing from the frequen of the first named oscillations by substantially equal and normally substantially constant amounts and from each other by substantially twice that amount., and means for varying said differences.

l1. A systemv for transmitting radiant energy, comprising means for producing local radio oscillations, means for wobbling the .frequency of said oscillations, means for producing therefrom and impressing on the Iether a plurality of series of waves having .frequencies differing from each other by a' normally constant amount, and manually operative means for varying said difference for transmitting a message.

12. A'system for transmitting radiant e11- Hiv lll)

comprising means for radio oscillations, varying .in frequency, means for producing therefrom and iinpressing on the ether two' series of waves having frequencies differing from the freergy,

Yquency of the rst named oscillations by substantially equal amounts and from each other by a substantially constant amount, and

Ameans for varying'said diiferences.

A system for transmitting radiant enlocal radio oscillations varying in frequency at a predetermined rate, means for producing therefrom and impressing on the ether two series of waves having a normally constant difference in frequency and differing from "the frequency of the first named oscillations by substantially equal amounts, and means for transmitting a signal comprising means for reducing the difference in' frequency between said series of waves. v

15. A- systemv for transmitting radiant energy, comprising means for producing local radio oscillations, means for varying the frequency of said' oscillations in a plurality of sequences, and means for producing from said oscillations and impressing on the ether two series of waves having frequencies differing from the frequencygof the first named oscillations .by substantially equal amounts and from each other by substantially. twice that amount, and manually l/operative means to reduce said differences to transmit a signal.

16. A system for transmitting radiant energy, comprising means for producing local radio oscillations, means for varying the frequency of said oscillations,'separate means fory Varying the frequency of said oscillations infaccordance with a false message pattern, means for .producing therefrom and impressing on the ether two series of waves having frequencies'differing froml the frequency of the first named oscillations by substantially equal amounts and from each other by substantially .twice that amount, and means for varying said differences according to a true message pattern. 17. A system for transmitting radiant energy, comprising means forfproducing local radio oscillations, means for varying the frequency of said oscillations, separate means for varying the frequency of 'said producing local forv producing local oscillations in accordance with a of false message patterns of unli e character, means for producing therefrom and Vimpressing on the ether two series of waves having frequencies 'dilfering from the frequency of the first named oscillations b substantially equal amounts and. fro eacli other by substantially twice -that amount, and means for Varying said differences according to a true message pattern.

18. A system for transmitting -adiant energy, comprisingA means for producing' means for.

oscillations of radio frequenc producing a plurality of series of oscillations therefrom differing in frequency from said oscillations vand from each other, means for impressing the last named series of oscillationsupon the ether, means for varying said frequency' differences to transmit desired signals, and receiving means constructed to utilize said 'frequency differences for reception of the signals..

19. A system for transmitting vradiant energy, comprising means for producing oscillations of radio frequency, means for producing a plurality of series of oscillations lplurality therefrom differing in frequency from said oscillations and from each other, means'for impressing the. last'named series of oscillations upon the ether, means for varying the manually operative' difference, in fre.

quency between a plurality of saidv series of l oscillations to transmit desired signals, and receiving means constructed to utilize said ldifference in frequency.

20. A system for `transmitting radiant energy, comprising means for producing alternating current of radio frequency, means for wobbling said current, means for .producing a plurality of series of 'oscillations therefrom differing in frequency from said currentand from each other by substantially constant amounts, means for impressing the last named series of oscillations upon the ether, and manually operative means for varying the difference frequencies for transmitting a message.

21. A system for transmitting radiant energy, comprising means for producing oscillations of radio frequency continually varyingin frequency, means for producing a plurality of serieslof oscillations therefrom differing in frequency from said oscillations and from each other, means for u `l rom differing in each other, ineens for impressing the last named series oi o1-riletions upon the ether, and means' for sluy cording to a true message pattern.

:23. A system for transmitting; radiant energy, comprising menne for producing osoil lotions of radio frequency continually ve'ying in frequeney at a predetermined ratefor a. period and einen changing the raie of change, means Afor producing e plurality of series oi osciiiaticns therefrom diierin in `frequency from said oscillations and rom eaeh. other, means for impressing the last named series of oscillations upon the eiher,

and means for varying said di'erenoes eccording to a ruemessage peti/ern.

24. A system for transmitting radiant energy, comprising means 'for producing osciliations of radio frequency continually verying in frequency et a. predetermined rate for e. period and then intermittently very ing the rate oehange, means for producing a. plurality of series of osciiiaiions therefrom differing in frequency from eeifi oscii lat-ions and from each other, ineens ier-1un- 'pressing the last named series of oscillations upon the ether, and means for varying said differences according to :i true message petdifferences ac- -mriance with a {aleeietions of radio frequency continuaily vary ing in frequency at a l'nedeermineri falte for.

a. yperiod and then intermittently varying the rate o chngefin accordance with a plurelity of false mefzsage patterns of unlike character, means for' producing a plurality of series of oscillations therefrom differing in requeneyv from said oscillations and from each other, means for impressing the' inst: named series of oscillgtions u on the ether, and means for varying said iii'eren-ces ucoordn to a true message pattern.

f 27. system or the transmission of radiant energy comprising meansI for roducing ioceiiy oscillations of a high ig'equency, means for wobbli the ,frequency of said oscillations, means or producing therefrom and impressing on lie ether e. plurality of series of waves having fr ueneiee iiiifer ing from the fre uency o'i t e first named oscillations by sueanially equal 'find non? *molly substanially constant; amountshami means for transmittin a signai oomprieing means for varying sai dierences.

28. A. system for the production of radi ont energy comprisin means for producing tivo' wobbied curren normally diiering .from eecii other bya substantially constant ernennt, and means for varying'saici diii'e1- ence.

Q9. A system for lthe production of rzu'lie'fi'c energy comprising .means for prfniueing two Wobbled curx'en'is norinallvfilii'eiing from each other by :i subsi-inicie ly constant. amount, :incl manufiiy operfiliie momie for Varying said difference for' transmitting; n. mei'sage,

'in testimony whereof we hereunto affixed om" signatures. 

